In this study, we evaluated the efficiency of two biocides, spinosad and ivermectin against two important stored grain insects, Sitophilus oryzae (L.) and Rhyzopertha dominica (F.) by using bioassay method, mixing with medium. Obtained results demonstrated that ivermectin had the highest effect on adult mortality for both insects using complete dose. Rates of spinosad or ivermectin from 50-150 ppm completely prevented emergence of adults of both insects. R. dominica was more susceptible to biocides tested than S. oryzae. Half-dose of spinosad or ivermectin nearly produced the same effect with complete dose on S. oryzae and R. dominica, while the one-third dose was less effect. The current results encourage using the half-dose instead of the full dose of both insecticides for controlling the tested insects to rationalize the insecticide application and to minimize their expected hazards.
Key words: Biocide, S. oryzae, R. dominica, Ivermectin, Spinosad
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